Research And Design Of Two-stage High-Frequency Amplifiers Based On SiGe/Si HBTs

This thesis discussed several problems occurred in the SiGe I-IBTs and its ICs?research process, and gave relevant solutions, ultimately, we manufactured two-stage high frequency amplifier based on SiGe I-LBTs.At first, in Chapter 2, to research quantitatively, an AC equivalent small signal circuit model for established layer structures was developed. In this step, we began from HIBTs?I functions, employed the Y-type and H-type circuit forms, established models and then calculated and discussed the difference between AC models of SiGe I-IBTs and Si BJTs. Using this kind of model, in the end of Chapter 2, an experimental phenomenon was explained successfully. In Chapter 3, we discussed the circuit forms of two-stage amplifiers; and in Chapter 4, we simulated the incipient layout on pt-substrates with the model, finally reached the two main factors that influence the frequency characteristics of the transistors and circuits, dimension and isolation methods. Aiming at the isolation, we developed and improved High Impedance Substrate Is land-Type Isolation structure used in Si substrates. In Chapter 6, we redesigned and improved the layout and came up with the final one. In this step, moreover, the effect of substrate impedance, base series resistance and the dimension of pads on frequency characteristics was simulated and discussed. We used several possible conditions and validated the efficiency of the developed island-type isolation method.